简介:利用Melnikov方法分析了含有5次方恢复系数项的Ф-Duffing-VanderPol振子系统在单势阱参数条件下产生Smale意义下混沌的必要条件。通过Poincare截面图、分岔图、Lyapunov指数谱等理论和数值方法,阐明了系统运动在单势阱参数下随周期激励信号变化的动态特性、复杂性和系统的非线性特征。最后,对单势阱参数条件下的中Ф^6-DVP振子的混沌自同步进行了进一步的研究,得到了很好的混沌同步控制结果。
简介:Anew3Dvelocitymodelofthecrustanduppermantleinthesoutheastern(SE)marginoftheTibetanplateauwasobtainedbyjointinversionofbody-andsurface-wavedata.Forthebody-wavedata,weused7190eventsrecordedby102stationsintheSEmarginoftheTibetanplateau.Thesurface-wavedataconsistofRayleighwavephasevelocitydispersioncurvesobtainedfromambientnoisecross-correlationanalysisrecordedbyadensearrayintheSEmarginoftheTibetanplateau.ThejointinversionclearlyimprovesthevSmodelbecauseitisconstrainedbybothdatatypes.Theresultsshowthatataround10kmdepththerearetwolow-velocityanomaliesembeddedwithinthreehigh-velocitybodiesalongtheLongmenshanfaultsystem.Thesehigh-velocitybodiescorrespondwellwiththePrecambrianmassifs,andthetwolocatedtothenortheastof2013MS7.0Lushanearthquakeareassociatedwithhighfaultslipareasduringthe2008Wenchuanearthquake.Theaftershockgapbetween2013Lushanearthquakeand2008Wenchuanearthquakeisassociatedwithlow-velocityanomalies,whichalsoactsasabarrierzoneforrupturesoftwoearthquakes.Generallylargeearthquakes(M≥5)intheregionoccurringfrom2008to2015arelocatedaroundthehigh-velocityzones,indicatingthattheymayactasasperitiesfortheselargeearthquakes.Jointinversionresultsalsoclearlyshowthatthereexistlow-velocityorweakzonesinthemid-lowercrust,whicharenotevenlydistributedbeneaththeSEmarginofTibetanplateau.